CN108682837B

CN108682837B - A kind of preparation method of oriented porous silicon material for lithium ion battery

Info

Publication number: CN108682837B
Application number: CN201810474753.4A
Authority: CN
Inventors: 郭军坡; 郑刚; 王辉; 刘会
Original assignee: Gotion High Tech Co Ltd
Current assignee: Gotion High Tech Co Ltd
Priority date: 2018-05-17
Filing date: 2018-05-17
Publication date: 2021-07-06
Anticipated expiration: 2038-05-17
Also published as: CN108682837A

Abstract

The invention discloses a preparation method of a lithium ion battery oriented porous silicon material. The steps are as follows: mixing sodium carbonate and silicon oxide, heating the mixture, and cleaning the mixture to obtain a lithium ion battery oriented porous silicon material. The present invention generates sodium silicate and elemental silicon by reacting silicon oxide and sodium carbonate in a high temperature environment, and then washing with deionized water to remove the sodium silicate and residual sodium carbonate generated by the reaction to obtain a structure with a large number of micropores, In order to build a channel suitable for the directional de/intercalation process of lithium ions and provide sufficient Li _x Si binding sites. At the same time, by choosing the abundant sodium resources in nature to gradually replace the scarce lithium resources, this has positive significance for rational utilization of resources and reduction of production costs. Using the oriented porous silicon material prepared by the invention as a negative electrode material in a lithium ion battery can improve the theoretical capacity and first cycle efficiency of the electrode material, thereby greatly improving the energy density of the material.

Description

Preparation method of directional porous silicon material for lithium ion battery

Technical Field

The invention relates to the technical field of micron silicon-based materials, in particular to a preparation method of an oriented porous silicon material for a lithium ion battery.

Background

Because the silicon source is rich, the price is low, the theoretical capacity is higher (4200mAh/g) and the platform potential is lower (0.5V), the silicon material is hopeful to replace the commercialized graphite and is applied to the negative electrode of the high-performance lithium ion battery. However, silicon is accompanied by severe volume change during lithium deintercalation, and it is difficult for silicon to form a stable Solid Electrolyte Interface (SEI) film in an electrolyte because of the destruction of an electrode structure due to such volume effect. Along with the damage of the electrode structure, a new SEI film is continuously formed on the exposed silicon surface, so that the corrosion and capacity attenuation of silicon are accelerated, and meanwhile, the material is continuously pulverized, active substances are continuously dropped, and the cycle performance of the battery is greatly reduced.

Based on the existing problems of the silicon-based negative electrode material, the invention designs the porous silicon material with the directional lithium-removing/lithium-inserting channel by continuously adjusting the structure of the silicon-based material so as to shorten the transmission distance of lithium ions; meanwhile, the stress change of the material in the lithium extraction process is inhibited by improving the content of active silicon and stable silicon in the material, and the first cycle efficiency of the battery and the cycle life of the battery are improved.

Disclosure of Invention

Based on the problems in the background art, the invention provides a preparation method of an oriented porous silicon material for a lithium ion battery, which is characterized in that the porous silicon material is prepared by focusing on the structural design of the silicon material, the transmission distance of lithium ions can be shortened, the obvious volume change of the silicon material in the circulating process is improved, the stress change of the silicon material in the lithium desorption process is inhibited, and a stable interface and an SEI (solid electrolyte interphase) film are maintained, so that the comprehensive performance of the battery is improved.

The invention provides a preparation method of a directional porous silicon material for a lithium ion battery, which comprises the following steps:

s1, mixing sodium carbonate and silicon monoxide to obtain a mixture;

and S2, heating the mixture for reaction, and cleaning to obtain the directional porous silicon material for the lithium ion battery.

Preferably, in S1, the mass ratio of the silicon oxide to the sodium carbonate is 0.2-1: 0.5-1.5.

Preferably, in S1, the particle size of the silica is 1 to 100 um.

Preferably, in S1, the particle size of the silica is 1 to 10 μm.

Preferably, in S1, the particle size of the sodium carbonate is 1-100 um.

Preferably, in S1, the particle size of the sodium carbonate is 1-10 μm.

Preferably, in S1, a three-dimensional blender is used for mixing.

Preferably, in S1, the specific operation of mixing is: adding the silicon monoxide into a three-dimensional mixer, then sequentially adding sodium carbonate and zirconium balls, controlling the material-ball ratio to be 1-10:1-10, and starting the three-dimensional mixer to mix for 2-5 h.

Preferably, in S2, an inert gas is used for protection during the temperature-rising reaction.

Preferably, the inert gas is at least one of argon and nitrogen.

Preferably, in S2, the temperature rise rate is 2-10 deg.C/min. The reason is that in the calcining process, the heating rate influences the effect of reducing the precursor, if the heating rate is too fast, the precursor mixture is heated unevenly, and the ideal effect cannot be achieved, so the heating rate is controlled to be 2-10 ℃/min.

Preferably, in S2, the reaction temperature is 800-1200 ℃.

Preferably, in S2, the reaction time is 2-6 h.

Preferably, in S2, deionized water is used for washing.

Preferably, the invention can be used for lithium ion battery negative electrode materials.

Preferably, the present invention can be used to make oriented porous silicon and silicon carbon composites.

According to the invention, the silicon monoxide and the sodium carbonate react at high temperature to generate sodium silicate and simple substance silicon, and then the sodium silicate generated by the reaction and the residual sodium carbonate are removed by using deionized water to obtain the directional porous silicon material for the lithium ion battery. The porous silicon material prepared by the invention is compounded with the carbon material and then used as a negative electrode material to be applied to a lithium ion battery, and because the porous silicon material prepared by the invention has a large number of microporous structures, a channel suitable for a lithium ion de-intercalation process can be constructed, an ideal binding site is provided for lithium ions, and the volume change of the material in the charge and discharge process is greatly relieved; moreover, the carbon material has higher conductivity and ion path, and the combination of the carbon material and the electrolyte can prevent silicon from directly contacting with the electrolyte, reduce the irreversible capacity, and improve the theoretical capacity and the first cycle efficiency of the electrode material, thereby greatly improving the energy density of the material. The preparation method is simple and easy to operate, has low cost, can be applied to various porous silicon and silicon-carbon composite materials, has good adaptability, and is suitable for large-scale production. Meanwhile, the invention takes sodium carbonate as a reaction raw material, and the abundant sodium resource in the nature is selected to gradually replace the scarce lithium resource, which has positive significance for reasonably utilizing the resource and reducing the production cost. In addition, the yield of the oriented porous silicon material for the lithium ion battery is more than 70%.

Drawings

FIG. 1 is a structural diagram of an object image of an oriented porous silicon material for a lithium ion battery prepared by the present invention;

FIG. 2 is a pore size distribution curve diagram of the directional porous silicon material for lithium ion battery prepared by the present invention;

fig. 3 is a charge and discharge graph of a lithium battery prepared using the oriented porous silicon material for a lithium ion battery of the present invention.

Detailed Description

The technical solution of the present invention will be described in detail below with reference to specific examples.

Example 1

A preparation method of an oriented porous silicon material for a lithium ion battery comprises the following steps:

s1, mixing sodium carbonate and silicon monoxide to obtain a mixture;

Example 2

s1, adding the silicon monoxide into a three-dimensional mixer, then sequentially adding sodium carbonate and zirconium balls, controlling the material-ball ratio to be 10:1, starting the three-dimensional mixer, and mixing for 5 hours to obtain a mixture; the mass ratio of the silicon monoxide to the sodium carbonate is 0.2: 1.5; the particle size of the silicon monoxide is 1-100 um; the particle size of the sodium carbonate is 1-100 um;

and S2, transferring the mixture into a tubular furnace, heating at a heating rate of 10 ℃/min under the protection of argon, keeping the temperature for reaction for 6 hours when the temperature reaches 800 ℃, cleaning with deionized water, and drying to obtain the directional porous silicon material for the lithium ion battery.

The obtained directional porous silicon material for the lithium ion battery is subjected to X-ray diffraction, the object image structure of the material is shown in figure 1, wherein diffraction peaks at 27 degrees, 47 degrees, 56 degrees, 69 degrees and the like respectively correspond to (111), (220), (311) and (400) crystal faces of simple substance silicon, and the simple substance silicon is generated after the silicon monoxide and the sodium carbonate are subjected to high-temperature reaction and washing treatment;

the pore size distribution of the oriented porous silicon material for the lithium ion battery obtained in the present embodiment is detected, and as shown in fig. 2, it can be known from fig. 2 that the pore size distribution range of the oriented porous silicon material for the lithium ion battery obtained in the present embodiment is significantly increased and is concentrated below 10nm, which has great effects on shortening the migration rate of lithium ions and alleviating volume change;

the directional porous silicon material for the lithium ion battery obtained in the embodiment is used as a negative electrode material to assemble the lithium ion battery, and the charge and discharge performance is detected, and as shown in fig. 3, the first charge capacity of the lithium ion battery is larger than 1842mAh/g (0.8V), and the first cycle efficiency is 71.2%.

Example 3

s1, adding the silicon monoxide into a three-dimensional mixer, then sequentially adding sodium carbonate and zirconium balls, controlling the material-ball ratio to be 2:9, starting the three-dimensional mixer, and mixing for 3 hours to obtain a mixture; the mass ratio of the silicon monoxide to the sodium carbonate is 0.3: 1; the particle size of the silicon monoxide is 1-10 um; the particle size of the sodium carbonate is 1-10 um;

and S2, transferring the mixture into a tubular furnace, heating at a heating rate of 4 ℃/min under the protection of nitrogen, keeping the temperature for reaction for 3 hours when the temperature reaches 900 ℃, washing with deionized water, and drying to obtain the directional porous silicon material for the lithium ion battery.

Example 4

s1, adding the silicon monoxide into a three-dimensional mixer, then sequentially adding sodium carbonate and zirconium balls, controlling the material-ball ratio to be 8:3, starting the three-dimensional mixer, and mixing for 4 hours to obtain a mixture; the mass ratio of the silicon monoxide to the sodium carbonate is 0.8: 0.5; the particle size of the silicon monoxide is 1-10 um; the particle size of the sodium carbonate is 1-100 um;

and S2, transferring the mixture into a tubular furnace, heating at a heating rate of 8 ℃/min under the protection of argon, keeping the temperature for reaction for 5 hours when the temperature reaches 1100 ℃, washing with deionized water, and drying to obtain the directional porous silicon material for the lithium ion battery.

Example 5

s1, adding the silicon monoxide into a three-dimensional mixer, then sequentially adding sodium carbonate and zirconium balls, controlling the material-ball ratio to be 1:10, starting the three-dimensional mixer, and mixing for 2 hours to obtain a mixture; the mass ratio of the silicon monoxide to the sodium carbonate is 1: 0.5; the particle size of the silicon monoxide is 1-100 um; the particle size of the sodium carbonate is 1-10 um;

and S2, transferring the mixture into a tubular furnace, heating at a heating rate of 2 ℃/min under the protection of nitrogen, keeping the temperature for reaction for 2 hours when the temperature reaches 1200 ℃, washing with deionized water, and drying to obtain the directional porous silicon material for the lithium ion battery.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. a preparation method of directional porous silicon material for lithium ion battery, is characterized in that, comprises the following steps:

S1, mix sodium carbonate and silicon oxide to obtain a mixture;

S2, subjecting the mixture to a heating reaction and cleaning to obtain a directional porous silicon material for lithium ion batteries;

Wherein, in S2, the reaction temperature is 800-1200°C; in S2, the reaction time is 2-6h;

In S1, the specific operation of mixing is as follows: the material-to-ball ratio is controlled to be 1-10:1-10, and the mixing is performed for 2-5 hours.

2. preparation method according to claim 1 is characterized in that, in S1, the mass ratio of silicon oxide and sodium carbonate is 0.2-1:0.5-1.5.

3 . The preparation method according to claim 1 , wherein, in S1 , the particle size of the silicon oxide is 1-100 μm. 4 .

4 . The preparation method according to claim 1 , wherein in S1 , the particle size of the silicon oxide is 1-10 μm. 5 .

5. The preparation method according to claim 1, wherein in S1, the particle size of the sodium carbonate is 1-100 μm.

6. The preparation method according to claim 1 or 2, wherein in S1, a three-dimensional mixing tank is used for mixing.

7 . The preparation method according to claim 1 , wherein in S2 , inert gas protection is used in the temperature-raising reaction process. 8 .

8. The preparation method according to claim 1 or 2, characterized in that, in S2, the heating rate is 2-10°C/min.